Pallet trucks often are used to lift and maneuver pallets and goods supported thereon during warehousing and for shipping or transportation. Pallet trucks have been developed to provide varying amounts of functionality to an operator and may be generally categorized as either manual or powered. Manual pallet trucks typically include a truck frame having a load lift portion that includes a frame with forks connected thereto, a base support portion or truck which has at least one rear wheel, and a hydraulic jack connected to the load lift portion and base support portion. The hydraulic jack, which is typically a hydraulic bottle jack, is operated by pivotally pumping up and down an operating handle, with the pumping causing the hydraulic bottle jack to raise the frame and the forks of the load lift portion relative to the base support portion or truck and the ground surface.
Once a pallet on the forks of a manual pallet truck has been raised by pumping the operating handle, an operator may steer the pallet truck by using the operating handle as a tiller arm to steer the rear wheel relative to the base support portion or truck. The operating handle is connected to the hydraulic power unit and the at least one rear wheel, such that moving the operating handle to the left or right generates concurrent turning of the hydraulic power unit and the at least one rear wheel. With the pallet raised, the operator pushes or pulls on the operating handle with sufficient force to maneuver the pallet truck, the pallet, and the goods on the pallet to a desired location. As is apparent, maneuvering the pallet truck, the elevated pallet, and the goods thereon is even more difficult when the pallet truck is positioned on an inclined or bumpy surface or within relatively tight confines, such as when offloading pallets from a semi-truck trailer.
A powered pallet truck includes a truck frame having a load lift portion that includes a frame with forks connected thereto, a base support portion or truck having a rear wheel, a hydraulic jack connected to load lift portion and base support portion, and a drive mechanism connected to the rear wheel that assists the operator in maneuvering the pallet truck. Like the manual pallet truck, the powered pallet truck has an operating handle pivotally connected to the hydraulic jack and that serves as a tiller arm that is connected to the rear wheel and rotatably connected to the base support portion or truck, such that moving the operating handle to the left or right causes concurrent turning of the hydraulic jack and the drive wheel for steering the pallet truck. However, the powered pallet truck has a drive mechanism, such as an electric motor, coupled to the rear wheel, which allows an operator to propel and brake the pallet truck by way of controls on the operating handle. This type of pallet truck may be referred to as a powered or a semi-powered pallet truck, as the operator still pumps the pivotable operating handle to activate the hydraulic jack to raise the load lift portion and the forks thereof relative to the base support portion or truck and the ground surface.
An operator, such as an employee of a local delivery service, may make a large number of deliveries throughout a workday wherein each involves loading and unloading pallets and the goods thereon. Requiring the operator to manually pump the operating handle of the pallet truck each time they need to lift a pallet may be ergonomically difficult, particularly when the operator is attempting to move a pallet in limited working areas.
At present, semi-powered pallet trucks are widely used in the material handling and transportation fields, but the hydraulic cylinder and oil storage cavity for the hydraulic jack are separated, with the hydraulic cylinder above the oil storage cavity, causing the height of the hydraulic cylinder to be very high relative to the ground. This, in turn, causes the hydraulic cylinder and oil storage cavity to require more packaging space and the base of the operating handle to be at a relatively high location. This further causes the truck size to be much taller, and increased cost of production and transportation of the pallet truck. In addition, when seeking the same overall truck height configuration, having the base of the operating handle be connected to the hydraulic jack at a higher location on a semi-powered pallet truck may cause the operating handle to be much shorter in length than the similar components on a manual pallet truck. Unfortunately, the shorter operating handle of the powered pallet truck will require more physical effort to operate than the handle of the manual pallet truck.
The drive system of a pallet truck is controlled by a controller. Traditional pallet thick controllers are fixed on a load lift portion or frame having forks. However, the operating handle and the drive motor are installed with parts that are connected to a base support portion that is rearward of the load lift portion. The operating handle and drive motor also tend to rotate left or right relative to the base support portion for steering the pallet truck. With the controller on the forward load lift portion, an output cable on prior art pallet trucks connects the controller and drive motor while they are on parts that pivot and move upward and downward relative to each other. Similarly, a control wiring or harness connects the controller to the operating handle to transmit control signal inputs and current outputs based on operator inputs while the controller and operating handle are on parts that also pivot and move upward and downward relative to each other. During lifting and turning, the output cable and control wiring or harness will follow the disparate movement of the respective parts to which they are connected. As a result, the movement of the control wiring and output cable will be subject to bending and torsion, and may interfere with each other. Long term use with such control wiring and cable routing will tend to result in fatigue fracture of the output cable and control wiring, wherein the control wiring or harness of a prior art pallet truck may be more easily broken. This type of wear and fracture may greatly reduce the service life of the control harness, and in turn, increase the maintenance cost of the pallet truck.